On Little Richard's birthday, LIFE features photos -- none of which have ever been published before -- of the man many credit as the true originator of rock and roll.

It will probably come as no surprise to those familiar with LIFE magazine — especially the LIFE of the 1950s and 1960s — that a pop-culture phenomenon as strange and as raw as Little Richard was not likely to appear frequently (or at all) in the magazine’s pages. But then, truth be told, LIFE missed the boat when it came to covering more than a few of the seminal characters in rock history: Elvis, Hendrix, the Stones — the very edgiest, or the less easily categorized, figures of those pivotal decades were often ignored or, at best, mentioned only occasionally by the influential weekly.

Maybe the magazine’s reluctance stemmed from, say, the fact that “Elvis the Pelvis” was a shock to some (primarily white) sensibilities in the 1950s, or that gloriously sordid rock gods like the Stones were, from the very start, exactly the sort of characters who made all of those lame jokes about “locking up your daughters” seem not so funny after all. These guys — along with wild women like Janis Joplin — projected an explosive sexuality and a touch of real menace that LIFE seemed to have a hard time making its own, or making sense of.

Movie stars like Liz Taylor and Sophia Loren could be, and frequently were, celebrated in LIFE for their sex appeal, appearing on the magazine’s cover striking poses and wearing outfits that were, if one squinted just right, downright salacious. But let rock and rollers cross that invisible line between Hollywood’s idea of the erotic and the delightedly raunchy approach to the topic taken by, say, Zeppelin, and the latter’s chances of showing up in LIFE sank very close to nil.

All of which makes the Little Richard photographs in this gallery, taken by LIFE’s Ralph Morse in 1971, all the more fascinating, and mysterious. None of these pictures ever ran in LIFE, and there’s no indication in the LIFE archives of why they were taken in the first place. Morse, for his part, doesn’t remember making them (“I have no idea who that guy is,” More, who is 96 years old and still sharp as hell, recently told LIFE.com when shown a few of the photos), which suggests that they might have been part of an impromptu photo shoot — perhaps at the Time & Life Building in New York, or maybe backstage at a concert — and that they were never meant to appear in the magazine at all.

What’s certain is that, four decades after they were made, these portraits of the Macon, Ga., native — published here on Little Richard’s 81st birthday (he was born Richard Wayne Penniman on Dec. 5, 1932) — capture at least a small part of the unnerving, unhinged charisma of the man many credit as the true originator of rock and roll. Little Richard, his backers argue, was the first true, living, breathing, screaming bridge between R&B and rock.

An ordained minister whose immediate and extended family is strongly evangelical, Penniman has also preached the Gospel to small rural congregations and to stadium-sized audiences of thousands.

By the time Morse made the pictures in this gallery, Little Richard’s ability to shock audiences had long since been surpassed by acts like Alice Cooper (good-natured vaudeville ghoul) and the Stooges (chaotically drug-addled Motor City lost boys). But decades after he became a star, his signature, wild-eyed polysexual look was still something to behold. In fact, it’s somehow heartening to think that even in the heady, let-it-all-hang-out years of early 1970s, the man who had galvanized the youth of the world in the 1950s by singing “Good golly, Miss Molly / You sure like to ball!” was still enough of an unclassifiable rebel that LIFE didn’t know what to make of him, and so let him be.

In the meantime, happy birthday, Little Richard. May you wop-bop-a-loo-bop-a-wop-bam-boom for many years to come.